Al-Matalib al-'Aliyah 4172 — Prohibition of speaking ill

It is narrated from Khaythamah (may Allah have mercy on him) that Sayyiduna Sa'd bin Abi Waqqas (may Allah be pleased with him) was present in a gathering of some people, when the people there mentioned Sayyiduna Ali (may Allah be pleased with him) and reviled him. Sayyiduna Sa'd (may Allah be pleased with him) said (rebuking them): "Refrain from speaking about the Companions of the Messenger of Allah (peace and blessings be upon him), for we committed an error while with the Messenger of Allah (peace and blessings be upon him), and Allah, the Mighty and Majestic, revealed this verse: 'Were it not for a decree from Allah that had already gone forth, a great punishment would have touched you for what you took (the ransom)' [Surah al-Anfal: 68]. And I have strong hope from Allah that a decree of mercy from Allah Almighty has already gone forth in our favour." Then one of them said (to provoke Sayyiduna Sa'd): "By Allah, he (Ali, may Allah be pleased with him) used to hate you and used to call you 'al-Ukhaynis' (the one with the flattened nose)." Hearing this, Sayyiduna Sa'd (may Allah be pleased with him) burst out laughing until laughter overcame him. Then he said: "Does it not happen that a man feels some resentment in his heart against his brother over some (mutual) matter, yet that (resentment) does not affect his trustworthiness and integrity (and his acknowledgement of the other's virtue)?" And he said something else as well.
This chain is sahih (authentic), and this narration contains great benefits.